Along with the recent rapid spread of information-related devices and communication devices such as a personal computer, a video camera, and a cell phone, development of a battery utilized as a power source of them is important. In the automobile industry and the like, development of a high-power and high-capacity battery for electric vehicles or hybrid vehicles has been proceeding. Currently, among various types of batteries, a lithium battery becomes a focus of attention in terms of high energy density.
Since currently commercially available lithium batteries employ a liquid electrolyte containing a flammable organic solvent, it is necessary to install a safety device which suppresses an increase in temperature in the event of a short circuit and improve a structure and a material for short-circuit prevention. On the other hand, all solid lithium batteries which replace an liquid electrolyte with a solid electrolyte layer and are fully solidified do not use a flammable organic solvent in the batteries. For this reason, it is considered that the safety devices for the all solid batteries are simplified and the all solid lithium batteries are excellent in production cost and productivity. As a solid electrolyte material used in such a solid electrolyte layer, a sulfide solid electrolyte material has been known.
Since the sulfide solid electrolyte material has a high Li ion conductivity, this is useful to attain high output of a battery, and various studies have been conducted. For example, Patent Literature 1 discloses sulfide-based crystallized glass in which a glass phase mainly composed of Li2S and P2S5 and a crystal phase exist.